The W5100 provides a network (IP) stack capable of both TCP and UDP. It supports up to four simultaneous socket connections. Use the Ethernet library to write sketches which connect to the internet using the shield.
Ethernet Shield W5100 for Arduino UNO, Mega 2560,1280 AVR
MAC address: 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

Technical Details

Product Details

Product Dimensions

Package Dimensions
Width : 3.2 inch
Height : 1.2 inch
Length : 5 inch

Item Weight: 0 ounce (View shipping rates and policies)
Shipping Weight: 0 ounce (View shipping rates and policies)

ASIN : B00VUS2BA8